# Sigma Notation

Sigma Notation enables to write a sum of many terms in a sequence in compact form. We have used the sigma notation to represent the sum of a finite number of terms in arithmetic and geometric sequences. The Greek letter ∑ corresponds to English letter S, hence used as a notation to represent sum.

The simplest form of sigma notation consists of the letter ∑ with boundary values written on top and bottom and the general term of the sequence is written inside the notation. This when expanded shows all the terms of the sequence summed up as shown below.

$\sum_{i=1}^{n}a_{i}$ = a_{1} + a_{2} +.......+ a_{n}.